Olefin polymerization catalyst systems are an important commercial technology. In many instances these catalyst systems contain a transition metal complex which is essential to their catalytic activity. In recent years, polymerization catalysts containing late transition metals such as iron, cobalt, palladium and nickel have been developed, and in some instances these polymerization catalyst systems make unique polymers. It is well known in the art that polymerization catalysts containing transition metals are often advantageously used when the transition metal (complex) is part of a supporting material such as a polymer or an in-organic compound such as silica, alumina, a magnesium halide, etc. These supported catalysts are especially useful in so-called gas phase or liquid slurry polymerization processes.
In a simple process for supporting a transition metal containing polymerization catalyst, a solution of the appropriate transition metal compound is mixed with the desired support and the solvent is evaporated. In many such instances the transition metal containing polymerization catalyst may simply be coated (as paint is coated on a wall) onto the support and may be removed. In some instances, the support such as silica may be prereacted with another compound of the polymerization system such as an alkylaluminum compound and then this support mixed with the transition metal containing polymerization catalyst.
Another less common way to affix the transition metal containing polymerization catalyst to a support is through a covalent bonded linkage which is attached to both the support and the transition metal containing polymerization catalyst, see for instance EP-A-0953580 which describes the preparation of a heterogeneous catalyst containing metallocene-type catalysts. Metallocenes have anionic ligands.
U.S. Pat. No. 6,030,917 describes methods for making supported polymerization catalysts containing late transition metals having neutral ligands attached to them. In the methods described therein, the ligand is attached to the support first and then ligand is coordinated with the desired transition metal.
WO00/56786 and WO00/56787 describe the preparation of supported transition metal polymerization catalysts in which the transition metal is complexed to an anionic ligand, but not to a neutral ligand.
WO99/28352 describes the preparation of various supported polymerization catalysts containing transition metals. Some neutral ligands are used, but the metal is not complexed with the ligand until after the ligand is attached to the support.
U.S. Pat. No. 5,955,555 and WO99/12981 describe the use of certain iron and cobalt complexes containing neutral tridentate ligands as olefin polymerization catalysts. Although supported catalysts are mentioned, no mention is made of having reactive groups on the neutral tridentate ligands.
All of the above-mentioned publications are incorporated by reference herein for all purposes as if fully set forth.